1. Field of the Invention
The present invention concerns gas lasers in which a stimulated emission is obtained subsequent to an electric discharge in a gaseous active medium.
2. Description of the Prior Art
Gas lasers comprising a longitudinal cavity containing the active gas and in which the electric discharge is obtained by means of a progressive current wave, propagating in the active medium from one end to the other of the cavity with a speed equal to that of the propagation of a stimulated light emission in that cavity are known.
Such gas lasers comprise a flat electric line, consisting of an insulating plate inserted between a first and second metallic plate brought to different potentials and excitation means for generating a discharge wave in that line.
The gaseous active medium is arranged in a longitudinal slot formed in one of the metallic plates of the line, on the path of the discharge wave.
To great advantage, the edges of the plates are in the shape of parabolas whose axis forms an angle .alpha. greater than zero with the axis of the slot.
Moreover, the progressive current wave is generated by means of a circuit suitable for setting up a substantially punctual discharge between the said metallic plates at the level of the focusses of the parabolas.
Nevertheless, it has been observed that in such lasers, the progressive wave of the current can have irregularities in propagation in the said active medium, this resulting in disturbances in the stimulated emission in the cavity.
Such a disadvantage, which appears after a certain period of operation, results more particularly from a variation in the electric properties between the portions of the metallic plates arranged on either side of the axis of the parabolas.
The present invention makes it possible to overcome such a disadvantage and it concerns a new structure of gas laser generator having strictly stable operation while making it possible to obtain an emission of coherent light having high power.
The invention therefore has as its object a laser generator comprising:
A gaseous active medium; PA1 At least one electric excitation line formed by an insulating plate inserted between a first and second metallic plate which are parallel to each other, the said first metallic plate having at least one slot separating it into two distinct parts; PA1 Means for maintaining a gaseous active medium in the said slot comprising a longitudinal insulating blade closing the slot and fixed on the said two parts of the first metallic plate; PA1 A circuit for setting up a substantially punctual discharge between the said metallic plates suitable for generating a progressive current wave in the said line, characterized in that at least said metallic plates are each cut in the shape of a half parabola, the pseudo-focusses as well as the pseudo-apexes of those half parabolas being respectively arranged on a same straight line perpendicular to the plane of the plates, the rectilinear part of the said half parabola forms an angle .alpha. which is greater than zero with the said slot, and the circuit means for setting up a discharge generating said progressive current wave discharges at the level of the pseudo-focusses of the said half parabolas.